A short-wavelength, high-power blue laser is expected to be more widely used in an optical pickup or the like. In general, plastic is easily damaged by a laser. Therefore, some optical parts of devices using a short-wavelength, high-power blue laser consist of glass instead of plastic to avoid damage by a laser. For this reason, the prices of devices are relatively high. The relatively high prices are a hurdle to be overcome to enlarge the market of the devices.
At present, plastic materials which can cope with a relatively-low-power blue laser are supplied from various material manufacturers. However, there is no plastic material which can withstand a high-power blue laser.
On the other hand, an antireflection film is frequently formed on surfaces of plastic lenses used in video camcorders, still cameras, glasses, and the like. Such an antireflection film consists of a multi-layered film obtained by alternatively stacking low-refractive-index layers and high-refractive-index layers. The multi-layered film is described in Japanese Patent Application Laid-Open Nos. 11-30703, 11-171596, 11-326634, 2002-71903, 2003-98308, 2003-248102, and the like. However, a conventional antireflection film cannot prevent a damaged caused by a high-power blue laser.
Since there is no plastic material which can withstand a high-power blue laser, in order to realize an optical element which can withstand a high-power blue laser using a plastic material, a method of forming a laser damage suppression film such as an antireflection film on a surface of a substrate consisting of a plastic material may be used.